I was not surprised to look it up and find that this episode was written by Ben Edlund, to my recall he's written some good Angel eps.
Anyway, Jaynestown is another great episode in my book. It has one of those things that I love about Whedon's show which is that they can start out in a very funny place, and end up in a very sincere and grim place. The whole thing with Jayne - from him trying to disguise himself, to the reveal of his hero-hood, to his acceptance of this hero role, and then finally getting to see some kind of softness, humanity, in him at the end is brilliant.
The crew's reactions are also lovely. Especially Wash cracks me up.
This ep also has another of my favorite things which is Sheperd's hair and River's reaction to it. Love it! Also love her "fixing" of books.
"Keep walking, preacher man!"
Oh, another love of mine, shown only in glimpses, is the relationship between Mal and Kaylee. I find it very sweet.